Tawosret ruled egypt jointly with Chancellor Bay as regent for her young step-son, after her own son died before he could take the throne. When Siptah died after on ly a short reign, she took the throne for herself and assumed the role of pharaoh and the titulary of a Queen. She counted her reign from the beginning of her regency, which may be why Manetho gave her seven years. During this timem Chancellor Bay probably continued to share the rule. According to some stories, Bay may have had her executed once she relinquished the keys to the treasury

She has a monumental tomb in the Valley of the Kings, which show her as beloved wife of Seti II. It is possible that her mummy is that of "unknown Roman" (misdated, obviously) from the cache in KV 35. Her tomb, KV 14, is one of the largest tombs in the valley and may have also included her husbands burial as well. It was built in three stages -- while she was Queen under Seti II, during her regency of Siptah, and when she ascended the throne herself.

Chancellor Bay is a shadowing figure who was coregent for Siptah along with Tawosret. He may have ruled by himself for a year or so after Tawosret's death in 1185 or so, accoridng to Piccione. Most egyptologists relegate him to the background, ruling from behind the throne while Tawosret sat in it. He was originally a scribe, and is referred to as "The Kingmaker" and "The self-made Man", which may imply that he was an usurper.